材料力学双语教学学习资料
材料力学(双语)Bending弯曲
Chapter 4 Internal Forces in BendingMECHANICS OF MATERIALS 材料力学（双语）Content§4.1 Concept of symmetrical bending and calculation sketch of the beam §4.2 The shearing force and bending moment of the beam §4.3 The shearing-force and bending-moment equations · the shearing-force and bending-moment diagrams §4.4 Relations among the shearing force、the bending moment and the density of the distributed load and their applications §4.5 Plot the bending-moment diagram by the theorem of superposition §4.6 The internal-force diagrams of the planar rigid frames and curved rods2目录§4.1 对称弯曲的概念及梁的计算简图 §4.2 梁的剪力和弯矩 §4.3 剪力方程和弯矩方程 ·剪力图和弯矩图 §4.4 剪力、弯矩与分布荷载集度间的关系及应用 §4.5 按叠加原理作弯矩图 §4.6 平面刚架和曲杆的内力图34.1 Concept of symmetrical bending and calculation sketch of the beam1. Concepts of Bending 1). BENDING(弯曲): The action of the external force or the external couple vector perpendicular to the axis of the rod makes the axis of the rod change into curve from original straight lines, this deformation is called bending. 2). BEAM（梁): The member of whose deformation is mainly bending is generally called beam.43). Practical example in engineering about bending564). Symmetric bending(平面弯曲) After deformation the curved axis of the beam is still in the same plane with the external forces. P1 q P2MThe plane of symmetry7Unsymmetrical bending： If a beam does not possess any plane of symmetry, or the external forces do not act in a plane of symmetry of the beam with symmetric planes, this kind of bending is called unsymmetrical bending.82. Calculation sketch of the beamIn general supports and external forces of the beam are very complex. We should do some necessary simplification for them for our convenient calculation and obtain the calculation sketch.1). Simplification(简化) of the beamsIn general case we take the place of the beam by its axis.2). Simplification of the loads (荷载)The loads (including the reaction) acting on the beam may be reduced into three types：concentrated force、concentrated force couple and distributed force.3). Simplification of the supports (支座条件)9①Fixed hinged support固定铰支座2 constraints，1 degree of freedom. Such as the fixed hinged support under bridges.②Movable hinged support可动铰支座1 constraint，2 degree of freedom. Such as the movable hinged support under the bridge.10θA BDB R RA A AB B B0.50.50.5P0.5PP0.50.50.5P0.5PP 0。
材料力学双语教学学习资料
材料力学双语教学学习资料材料力学是工程院校中的一门重要课程，主要研究材料的力学特性和变形行为。
在学习材料力学的过程中，双语教学学习资料能够帮助学生更好地理解和掌握相关知识。
以下是一份关于材料力学双语教学学习资料，帮助学生深入了解材料力学的基本概念、原理和应用。
材料力学的基本概念-弹性模量：弹性模量是材料力学中衡量材料刚性的重要参数，表示单位面积内材料应力和应变的比例。
弹性模量越大，材料的刚性越高。
-屈服强度：屈服强度是材料在受力过程中的临界点，超过该强度材料会发生塑性变形或破坏。
-韧性：韧性是材料在受力下能够吸收能量的能力。
韧性越高，材料在受力下变形的能力越好。
-硬度：硬度是材料抵抗划伤或磨损的能力。
硬度越大的材料，其表面越不容易被刮花或磨损。
材料力学的原理-应力和应变：应力是材料内部单位面积上的力，应变是单位长度的变形量。
材料力学研究的是材料在接受外力时的应力分布和应变行为。
-弹性和塑性：材料力学区分材料的应变行为，弹性是指材料受力后能恢复原状的能力，塑性是指材料在受力后发生永久性变形的能力。
-破坏和失效：材料力学研究材料受力后失效和破坏的原因和机制，例如强度不足、断裂、疲劳等。
材料力学的应用-结构设计：材料力学的基本原理可应用于工程结构的设计和分析，确保结构在受力时能够满足安全和稳定的要求。
-金属材料加工：材料力学研究金属材料的塑性变形行为，可应用于金属材料的成形和加工工艺的优化和控制。
-材料选择和性能评估：材料力学可以帮助工程师选择合适的材料，根据材料的力学性能评估材料的适用性和可靠性。
Material Mechanics Bilingual Teaching and Learning Materials Material mechanics is an important course in engineering schools, which mainly studies the mechanical properties and deformation behavior of materials. Bilingual teaching and learning materials can help students better understand and master the relevant knowledge in the process of learning material mechanics. Here is a bilingual teaching and learning material on material mechanics to help students deepen their understanding of the basic concepts, principles, andapplications of material mechanics.Basic Concepts of Material Mechanics- Elastic modulus: The elastic modulus is an important parameter in material mechanics that measures the rigidity of the material. It represents the ratio of stress to strain within a unit area. The higher the elastic modulus, the higher the rigidity of the material.- Yield strength: Yield strength is the critical point of the material during the application of force. If the stress exceeds this strength, the material will undergo plastic deformation or failure.- Toughness: Toughness is the ability of the material to absorb energy under stress. The higher the toughness, the better the material's ability to deform under stress.- Hardness: Hardness is the material's resistance to scratching or abrasion. A material with higher hardness is less likely to be scratched or worn on the surface.Principles of Material Mechanics- Stress and strain: Stress is the force per unit area inside the material, and strain is the change in length per unit length. Material mechanics study the stress distribution and strain behavior of materials under external forces.- Elasticity and plasticity: Material mechanics distinguishes the strain behavior of materials. Elasticityrefers to the ability of a material to recover its original shape after being subjected to force, while plasticity refers to the ability of a material to undergo permanent deformation under stress.- Failure and fracture: Material mechanics studies the causes and mechanisms of failure and fracture of materials under stress, such as insufficient strength, fracture, fatigue, etc.Applications of Material Mechanics- Structural design: The basic principles of material mechanics can be applied to the design and analysis of engineering structures to ensure that the structures can meet safety and stability requirements under stress.- Metal material processing: Material mechanics studies the plastic deformation behavior of metal materials, which can be applied to the optimization and control of metal materials' forming and processing techniques.- Material selection and performance evaluation: Material mechanics helps engineers select suitable materials and evaluate their applicability and reliability based on the mechanical properties of materials.。
Chapter 6. Bending Deformation 材料力学教学课件 英文版
x a :1 2 , v1 v2
To be continue…(出现了四个积分常 数，确定它们需要两个边界条件和两 个连续条件。计算过程较为繁琐)
Solution II : method of singular function (奇异函数法).
1. moment equations
x3
F 6
(x
a)3
C2x
D2
Chapter 6. Bending Deformation
6.3 Direct Integration Method Method of singular function (奇异函数法)
Fn
x
dx 1 n 1
xa
n1
Fn
x
xa
n
x an
0
(x a) (x a)
dFn x dx
利用奇异函数，可以将弯矩和剪力方程写成统一形式，
n
F0
x a n1
n0
无论有几个力区。基本步骤如下：
1
1. 采用统一坐标系，原点选在梁的左端；
a
x
2. 若均布载荷没有作用到最右端，将其延续到底，延续部分将 F1 作用反向均布载荷；
n 1
3. 在最右段用截面法列剪力、弯矩方程，用设正法；
6
24
3. boundary condition
max 8EIz
x l:v 0, 0
ql3 ( )
max 6EIz
C ql3 6
D ql4 8
Chapter 6. Bending Deformation
6.3 Direct Integration Method
英汉双语材料力学12
4
§12–1 SUMMARY OF STATICALLY INDETERMINATE
STRUCTURES Structures that the whole constraint reactions and the internal forces in such structures can not be determined only by the static equilibrium equations are all called statically indeterminate structures or systems. In the statically indeterminate structure the constraints in excess of the number needed to support the structure in a statically determinate manner are called static
11P 16
P
A
X 1l 3 5Pl3 0 3EI 48EI
5 X 1 P 16
(f)
3Pl 16
C
5P 16 5Pl 32
B
⑤Determine other constraint reactions. The reactions at the end A may be found out by the static equilibrium equations. Their magnitudes and directions are shown in Fig.(f).
P
A
X 1l 3 5Pl3 0 3EI 48EI
⑤求其它约束反力
5 X 1 P 16
材料力学A双语实验课程介绍
材料力学A双语实验课程介绍1.教学单位名称：机械科学与工程学院2.实验中心名称：力学实验中心3.课程名称：材料力学A（双语）4,课程代码：412155,课程类别：学科基础课6,课程性质：必修7,课程学时：96学时，其中含实验12学时8,课程学分：69,面向专业：机械工程、工程力学、机械工程（卓越工程师教育培养计划）；车辆工程、工业设计、能源与动力工程、车辆工程（卓越工程师教育培养计划）；交通工程（汽运）土木工程（路桥）汽车服务工程；农业机械化及其自动化、包装工程、农业机械化及其自动化（卓越工程师教育培养计划）10.实验课程的教学任务、要求和教学目的教学任务材料力学实验是《材料力学》教学中的一个重要环节，通过实验丰富学生的书本知识，增强学生的实践能力；更重要的是，提高学生应用实验的手段与方法去分析、研究和解决工程问题的能力；提高学生建立或者修正完善力学模型的能力。
通过力学实验还可以培养学生对一些新材料和新结构的研究能力，为以后解决力学研究中的实险问题打下一定的基础。
教学要求对低碳钢和铸铁等材料的拉伸、压缩、扭转力学性质有基本了解；学习材料力学性能测试的常规检测设备和基本操作方法;了解应变测量的电测原理，掌握电测基本方法；增强对组合变形及超静定结构力学特征的认识；对光测力学，疲劳破坏，冲击韧性测量等有初步了解。
教学目的材料力学实验课是材料力学课程的重要组成部分，是理工科专业技术基础课的基本实践教学环节。
通过该实践教学环节，验证课程中的相关知识，巩固和加深对材料力学基本理论的理解，增强力学分析意识与分析能力，提高力学检测、诊断和设计水平。
同时，学生在实验过程中，学习材料力学实验的基本内容，学会实验的实际操作，特别是材料试验机的操作，以及数据采集和分析的技能，掌握对材料进行基本力学性能测试的方法。
H.学生应掌握的实验技术及实验能力(1)掌握万能电子材料试验机及扭转试验机的基本原理和使用方法；(2)掌握在不同受力条件下材料力学性能的测试方法；了解不同材料在不同受力下破坏形式及其破坏原因；(3)掌握电测实验应力分析的基本方法；(4)掌握常用仪器的基本原理及使用方法；(5)掌握受力构件表面应力的测量方法；(6)了解光弹性应力分析、动应力测量、冲击和疲劳实验的基本原理和方法;（7）培养具有熟练整理实验数据、分析误差和独立完成实验报告的能力。
英汉双语材料力学9
Material Mechanics 9 材料力学9概述：材料力学是研究材料在外力作用下受力、变形及破坏规律的学科。
目前，材料力学已成为材料科学最为基础和重要的学科之一。
在现代科技和工业生产中，材料力学的应用越来越广泛。
材料力学的分支很多，其中包括了应力、变形、破坏、断裂、塑性、蠕变、疲劳、材料动力学、非线性力学等等。
一、应力应力指材料内部受到的载荷作用下发生的内力状态。
应力可以分为三种：正应力、剪应力和体应力。
正应力分为正向和负向两种，是指载荷由材料内部向外发出的面的垂直方向对面积的比值。
剪应力则是指载荷由材料内部向外发出的面的切向（平行于面）对面积的比值。
而体应力则是指材料内部所有面受到的载荷的合力对体积的比值。
二、变形变形是材料在外力作用下所发生的形状、尺寸、位置以及物理和化学性质等方面的变化。
变形可分为弹性变形和塑性变形，其中弹性变形指当材料受到外力之后，只会形成可逆的变形，即在释放外力后会回复到原有的形态。
而塑性变形，则是指在材料受到外力作用之后，会引起形态上的不可逆性变化。
三、破坏材料在受到外力作用下，可能会引起破坏，破坏可分为静态破坏和疲劳破坏。
静态破坏指在一定载荷作用时间后，材料内部发生的破坏现象，常见的有拉断、压碎、弯曲破坏等。
而疲劳破坏则是指在材料受到周期性变化载荷作用时，材料内部会发生渐进性的破坏现象，常见的有金属疲劳、材料疲劳等。
四、断裂断裂是指材料在外力作用下分裂开来的现象。
材料的断裂可以分为两种：韧性断裂和脆性断裂。
韧性断裂指在材料断裂的时候，能够发生一定程度的拉伸和变形，属于可塑性断裂。
而脆性断裂，则是指在材料发生断裂时，无法发生显著的塑性变形，即属于不可塑性断裂。
五、塑性塑性是指在材料受到外力作用时发生的非弹性变形，可以分为一般塑性、温度塑性和蠕变塑性等。
材料的塑性受到许多因素的影响，如温度、内部缺陷等。
六、蠕变蠕变是指材料在常温和高温下，在一定应力作用下呈现出的随时间延长而发生的塑性变形。
英汉双语材料力学14
As long as the maximum stress of the cycle stress does not exceed
a“the maximum limit”, a material may be subjected to millions of times
cycling without fatigue. This maximum stress is called the “fatigue limit”. It is
§14–3 材料持久限及其测定
一、材料持久限(疲劳极限)： 循环应力中的最大只要不超过某个“最大限度”,构件就可以经历无数次循环而
不发生疲劳破坏，这个限度值称为“疲劳极限”，用r 表示。
二、 —N 曲线（应力—寿命曲线）：
A
r
o NA
N(循环次 数)
N0
第19页/共66页
A—名义持久限。 N0—循环基数。 r—材料持久限。
formula by the shearing stress.
0 r
K
r
Under the case of a symmetric cycle, r = -1. All the above coefficients can be obtained by looking up tables.
第22页/共66页
designated by r .
2、 —N curve（Stress—life curve）：
A
A—Nominal endurance limit
N0—cycle base
r
o NA
N(cycling numbers)
r—Endurance limit of materials
(英汉双语)工程力学第零章 绪 论
12
Sun Xunfang is an engineering mechanist and mechanics educationist. He has engaged in the research of fracture, damage, fatigue and creep of solid mechanics .He is the first to apply fracture dynamics to practice and developed the method of analysis in elasto-plastic fracture dynamics with surface cracks and assessment in integrity .
Leonardo Da Vinci Galileo Galilei
He made a detailed study on the basic concepts of movement including the center of gravity ,speed and acceleration and came up with the rigid mathematic formulas .Especially the concept of acceleration is the milestone in the history of mechanics.
Strength、 rigidity、 stability
19
§0-2 材料力学的任务及与工程的联系
强度、刚度、稳定性
20
Strength :
Capacity to resist failure of a component or an element. Rigidity : Capacity to resist deformations of a component or an element. Stability : Capacity to remain the original state in equilibrium of a component or an element
材料力学(双语)压杆稳定
y(0) = y′(0) = 0; y( L) = y′( L) = 0
M0 A = 0, B = − , kL = 2nπ P
∴ kL = 2nπ
and
kL = nπ
In order to determine the minimum critical pressure“k”must be the minimum value except zero, that is：
π 2 EI min Pcr = ( μL ) 2
General form of Euler’s formula of the critical pressure
μ—Leng1 Euler’s formula of the slender compressive column under various constraint conditions
6
10.2 Euler Formula of Critical Load
1. Critical pressure for the column with two hinged ends
Suppose the pressure has reached the critical value and the column has been in tiny bending state as shown in the figure. Start to determine the critical force with the deflective curve.
P cr =
π 2 EI
l
2
P P cr ≈ cr ≈ cr ≈ 2 P 2 (0.5l) (0.7l) (2l)2
π 2 EI
π 2 EI
英汉双语材料力学13
一、动载荷：
§13-1 基本概念
载荷不随时间变化（或变化极其平稳缓慢）且使构件各部件
加速度保持为零（或可忽略不计），此类载荷为静载荷。
载荷随时间急剧变化且使构件的速度有显著变化（系统产生
惯性力），此类载荷为动载荷。
二、动响应：
构件在动载荷作用下产生的各种响应（如应力、应变、位
移等），称为动响应。
实验表明：在静载荷下服从虎克定律的材料，只要应力不
1、Dynamic stress of the body in the straight-line motion
Example 1 The effective area of the steel wire rope in a crane is A, [? ] is
known . Weight per unit volume of the body is ? and the body moves up at the acceleration a. Try to check the strength of the rope（neglect the weight of the
areaof the rotating arm（neglecting the weight of the rotating arm）.
GG
Solution：①The free body diagram is
shown inertia force is
O
GG ? man ? ? 2Rm ? ? 2LG / g
?
d
?
Nd A
?
1 (G? A
qL)(1?
a g
)
?
1 2.9?10
?
4
(50?103
英汉双语材料力学2
bolt
Characteristic：It can
P P
pass general loads and can be dismounted.
§2－1 连接件的剪切与挤压强度计算
一、连接件的受力特点和变形特点：
沿铆钉的剪切面剪断，如
沿n– n面剪断 。 ②挤压破坏 铆钉与钢板在相互接触面 上因挤压而使溃压连接松动，
Q n
P
发生破坏。
③拉伸破坏
钢板在受铆钉孔削弱的截面处，应力增大，易在连接处拉断。
2、Practical calculation of shear
Method of the practical calculation：According to possibility of breakage of the member some assumptions by which basic characteristic subjected to force actions can be reflected and calculations can be simplified are used. Then calculate its nominal stress, determine the corresponding permissible stress in accordance with the result of direct test. At last do the strength calculation. Applying range：volume of the member is not large and real stress is quite
材料力学专业英语1
The Importance of Learning English for Materials
Mechanics
Global Advantage
Access to Resources
Enhanced Career Prospects
Materials mechanisms are a field that transfers national boundaries, and the use of English as a common language enables professionals to collaborate and share knowledge worldwide
03
English Vocabulary for Materials
Mechanics
Vocabulary for mechanical properties of metallic materials
Elastic modulus
Yield strength
The ratio of stress to strain in a material under elastic deformation
Basic units and symbols of material mechanics
要点一
Summary
要点二
Detailed description
Overview of Basic Units and Symbols in Materials Mechanics
Common units used in material mechanics include SI units (such as Newton, meter, kilogram, etc.) and engineering units (such as pound force, foot, pound, etc.). In addition, there are some commonly used symbols to represent different physical quantities, such as σ Represents stress, ε Indicates strain, etc.
英汉双语材料力学11
L EA
L
GI P
M (x)M0(x)dx L EI
f A
M
L
(x)M0 (x)dx EI
二、普遍形式的莫尔定理
莫尔定理(单位力法)
A
N ( x)N0( x) dx M n ( x)M n0( x) dx
L EA
L
GI P
M (x)M0(x)dx L EI
3、What we must pay attention to as we apply Mohr’s theorem： ① M(x)：The internal force of the structure acted by original loads.
Example 3 Determine the displacement and the angle of rotation of point C by
the energy method .
q A
x
C
a
a
BA
P0 =1
B
C
a
a
Solution：①Plot the diagram of the structure acted by the unit load
a
U 2
1
( P x)2 dx P2a3
0 2EI 2
12 EI
W
U
fC
Pa 3 6EI
思考：分布荷载时，可否用此法求C点位移？ q
§11–2 MOHR’S THEOREM(METHOD OF UNIT FORCE)
q(x) A
1、Provement of the theorem：
Fig a
fA P0=1
Mechanics of Materials
英汉双语材料力学15 ppt课件
5. Explore the new rule from tests and check the theory of stress analysis and the
2020/11/29
5
calculation method.
§15–１ 概 述
一、实验应力分析方法的作用： 1.设计时，测定模型的应力或变形，依此来确定构件的合理尺 寸和结构形式。 2.工作中，测定构件的真实应力或变形，找出最大应力的位置 和数值，以评价工程结构的安全可靠性，并为提高设备的 工作能力提供依据。
3.对破坏或失效构件进行分析，提出改进措施，防止再次破坏。
4.测定外载的大小、方向以及各种动响应。
5.从试验中探索新的规律，并对应力分析理论和计算方法进行
202校0/11核/29 。
6
二、Brief introduction of methods in the stress analysis of experiments
tensile
Fig.14 Sketch of the tensile test
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of Galileo
Fig.15 Sketch of the bending test of Galileo
11
伽利略 (1564—1642)
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12
Mushenbluic (1692—1761)
Fig.37 Tensile-test machine of Mushenbluic
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Fig.38 Method to clamp two ends of a tensile specimen
13
穆申布洛依克 (1692—1761)
英汉双语材料力学15
穆申布洛依克 (1692—1761)
Hydraulic verstile testing machine controlled by the computer
2. Other methods：
Since the early 20th century,the developments of electricity,optics acousics and materials science have provided conditions for the productionof other measurement methods of the stress analysis in experiments.Then the resistancestrain method,ordinary photoelasticity method,hologram photoelasticity method,sound launching method and so on are made fast developments and wide applications.
3.对破坏或失效构件进行分析，提出改进措施，防止再次破坏。 4.测定外载的大小、方向以及各种动响应。 5.从试验中探索新的规律，并对应力分析理论和计算方法进行
校核。
二、Brief introduction of methods in the stress analysis of experiments
2.其它方法：
20世纪初至今，电学、光学、声学和材料科学的发展， 为试验应力分析其它测量方法的产生创造了条件。于是，电 阻应变法、普通光弹法、全息光弹法、散斑法、声发射法等 方法都有了快速发展和广泛应用。
§15–2 Principle and application of the strainometer of the resistance
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材料力学双语教学学习资料1 第一章绪论Chapter 1 Introduction§1-1 材料力学的任务The Tasks of Mechanics of Materials1＊. 材料力学: Mechanics of Materials2. 构件: Structural Members3. 变形: Deformation4＊. 强度: Strength5＊. 刚度: Rigidity6＊. 稳定性: Stability§1-2 变形固体的基本假设Fundamental Assumptions of SolidDeformation Bodies1. 连续性假设: Continuity2. 均匀性假设: Homogeneity3. 各向同性假设: Isotropy§1.3 外力及其分类External Forces and Classification1. 分布力: Distributed Force2. 集中力: Point Force3. 静载荷: Static Load4. 动载荷: Dynamic Load§1.4 内力、截面法和应力的概念Concepts of Internal Forces，Method ofSection and Stress1＊. 内力: Internal Force2＊. 截面法: Method of Section3. 截面法的三个步骤：截开，代替，平衡Three steps of method of section: cut off, substitute , and equilibrium.4＊. 应力: Stress5. 平均应力：Average stress6. 应力（全应力）：Whole stress（sum stress）7＊. 正应力: Normal Stress8＊. 剪应力(切应力)：Shearing Stress§1.5 变形与应变Deformation and Strain1．线应变: Strain2．剪应变: Shearing Strain§1.6 杆件变形的基本形式Basic Types of Deformations of Rods1＊. 拉伸或压缩: Tension or Compression2＊. 剪切: Shear3＊. 扭转: Torsion4＊. 弯曲: Bending第二章拉伸、压缩与剪切Chapter 2 Tension，Compression andShear§2.1 轴向拉伸与压缩的概念和实例The Concept and Examples of AxialTension and Compression1. 拉杆: Tensile Rod2. 压杆: Compressive Rod3. 受力特点：外力合力的作用线与杆轴线重合Characteristic of the External Forces: The acting line of the resultant of external forces is coincided with the axis of the rod.4. 变形特点：杆沿轴向伸长或缩短Characteristic of Deformation: Rod will elongate or contract along the axis of the rod.§2.2 轴向拉伸或压缩时横截面上的内力和应力Internal Force and Stress of Axial Tension or Compression on the Cross Section1＊. 横截面: Cross Section2＊. 轴力: Normal Force3＊. 轴力图: Diagram of Normal Force§2.3 直杆轴向拉伸或压缩时斜截面上的应力Stress of Axial Tension or Compressionon the Skew Section1. 斜截面: Skew Section2.ασσα2cos = αστα2s i n 2=§2.4 材料在拉伸时的力学性能Mechanical Properties of Materialswith Tensile Load1. 标准试件: Specimen2. 低碳钢(C ≤0.3%): Low Carbon Steel3. 弹性阶段:Elastic Region4. 屈服阶段:Yielding Stage5. 强化阶段:Hardening Stage6. 颈缩阶段: Necking Stage 7＊.σp ----比例极限: Proportional Limit 8＊.σe ----弹性极限: Elastic Limit 9＊.σs ----屈服极限: Yielding Stress 10＊.σb ----强度极限: Ultimate Stress 11. 延伸率: Percent Elongation12. 断面收缩率: Percent Reduction of Area 13. 塑性材料: Ductile Materials 14. 脆性材料: Brittle Materials 15. 铸铁:Cast iron§2.7 失效、安全系数和强度计算 Failure, Safety factor and Strengthcalculation1＊. 许用应力: Allowable Stress 2. 安全系数: Safety Factor 3＊. 强度条件: Strength Condition][max σσ≤=AF N4＊. 强度校核: Check strength][max σσ≤5＊. 截面设计: Section design][σNF A ≥6＊. 确定许可载荷:Determine allowable load][σA F N ≤§2.8 轴向拉伸或压缩时的变形 Deformation in Axial Tension orCompression1. 弹性变形: Elastic Deformation2. 塑性变形: Plastic Deformation3. 纵向应变: Longitudinal Strainll l l l -=∆=1ε 4. 横向应变: Lateral Straindd d d d -=∆=''ε5．线弹性变形:Linear Elastic Deformation6.泊松比:Poisson’s ratioεεμ'=7＊.弹性模量-E ：表示材料抵抗拉压变形的 能力 E - modulus of elasticity ：Indicates the capability of materials for resisting tension or compression 8＊.抗拉刚度-EA :表示构件抵抗拉压变形的能力EA -the axial rigidity: Indicates the capability of constructive members for resisting tension or compression 9＊. 胡克定律（Hooke’s Law ）:当应力不超过材料的比例极限时，应力与应变成正比.The stress is proportional to the strain within the elastic region.εσE =§2.12 应力集中的概念The Concept of Stress Concentration 1.由于截面尺寸的突然变化，使截面上的应力分布不再均匀，在某些部位出现远大于平均值的应力，称应力集中。
Discontinuities of cross section may result in high localized or concentrated stresses. 2. 理论应力集中系数K ：TheoreticalEA L F L N=∆Stress-concentration Factor - K§2.13剪切和挤压的实用计算Practical Calculation of Shear and Bearing 1＊. 剪切：Shear2.剪切面：Shearing Plane 3＊. 剪切面上的内力-剪力：Internal Force in Shearing Plane-Shearing Force4. 剪切的实用计算：Practical Calculation of Shear][ττ≤=AF S5. 挤压的实用计算：Practical Calculation of Bearing][bs bsbs A Fσσ≤=6. 挤压强度条件：工作中的挤压应力不应超过许用挤压应力。
Strength condition of bearing ：Working bearing stress should not exceed the allowable bearing stress.第三章 扭 转 Chapter Three Torsion§ 3.1 扭转的概念和实例 Concept and Examples of Torsion 1. 电动机: Generator 2. 涡轮: Turbine 3＊. 扭转的受力特点：杆件的两端作用着大小相等，方向相反，且作用面垂直于杆件轴线的力偶。
Characteristic of loads: Shaft is loaded by a torsional couple in planes that are perpendicular to the axis of the shaft. 4＊. 变形特点：杆件的任意两个横截面发生绕轴线的相对转动。
Characteristic of deformation: any two cross sections will twist along the axis. 5＊. 轴: Shaft§ 3.2外力偶矩的计算 扭矩和扭矩图 Calculation of the external torqueInternal torque and Its diagram1．扭转外力偶矩的计算：Calculation of the external torque 2＊. 扭矩：Internal Torque 3. 符号规定：Sign convention 4＊. 右手螺旋法则: Right hand screw rule 5＊. 扭矩图：Diagram of Internal Torque§ 3.3 纯剪切 Pure Shear1. 薄壁圆筒的扭转实验：Experiment of thin-walled circular tube under torsion2. 变形特点: Characters of deformations ： 截面间的距离不变;所有横截面的位置不变;所有纵向线转过了一个角度γ。